Calandria



Nwv. 11 1924.

J. J. ARMSTRONG 1 CALANDRIA Filed Sept. 9, 1920 with a large central opening and Patented Nov. ll, i924,

JOHN JAMES ARMSTRONG, OF LOS ANGELES, CALIFORNIA.

CALANDRIA.

" Application filed September To all whom it may concern: Be it known that 1, JOHN J. ARMSTRONG, a citizen ofthe United States, residing at Los Angeles, county of Los Angeles, State of California (whose post-office address is Higgins Building, Los Angeles, California), have invented certain new and useful Tmprovements in Calandrias; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled inthe art to which itappertains to make and use the same.

This invention relates to an -1mproved form of calandria for use in connection with either multiple effect evaporators OIVHCHUDI pans and has particular'reference to the type generally known as the tube-sheet type. In calandrias of this type heretofore used, the tubes were set either vertically, regardless of the angle at which the tube-sheets were placed or were disposed at right angles to the'tube-sheets, but in both instances the top and bottom tube-sheets were arranged parallel to each other, irrespective of the angle from the horizontal at which said tubesheets were positionec.

The principal and distinguishing feature of this invention resides in the position of the top tube-sheet with respect to that of the lower tube-sheet, the top tube sheet being placed horizontally orlapproxnnately so, and the lower tube-sheet placed on an angle from the horizontal, the tubes being vertically disposed in relation to the calandria as a whole. By this arrangement a better distribution of heat is assured and a greater heating surface obtained, as compared to calandrias of a corresponding,height, the height referred to being that of the calandria where it is supported in the walls of the vacuum pan or evaporator,

Briefly stated, the invention comprlses a calandria having an upper ortop tube-sheet, horizontally arranged, provided 'with the customary large central opening and a ser es of smaller openings, which latter openings are to accommodate the upper ends of the vertically arranged heating tubes. I The bottom or lower tube-sheet is arranged at an angle to the horizontal, being "also provided a series of vertically disposed smaller openings to accommodate the lower ends of the heating tubes in position between. the upper and lower tube-sheets, the two large centralopenings of said upper and lower tube-sheets 9, 1920. Serial No. 409,064.

being connected by a corresponding large cylinder or tube forming the central opening of the calandria, the calandria when assembled being positioned and supported in the walls of the vacuum pan in the customary manner, means also being provided for the entrance of the necessary steam for furnishing the desired heat during the operation of the apparatus.

Referring particularly to the accompanying drawing illustrating the preferred em bodiment ofthe present invention, the calandria designated generally as A is supported in the walls of the vacuum pan or evaporator B. The calandria A comprises an upper tube-sheet 1 arranged in substantially horizontal position and a lower tube-sheet 2 disposed at an angle to the horizontal, re-f sulting in a gradual increase in depth. of the calandria from the outer periphery toward the center thereof. The top tube-sheet l is provided with a series of uniformly arranged openings 3, which are adapted to receive and have secured therein vertically disposed heating tubes 4-. v

The lower tube-sheet 2 is likewise .provided with a series of uniformly arranged and vertically disposed openings 5, said openings being positioned directly beneath and concentric with corresponding openings 3 of the tube-sheet l, in order to receive the lower ends of the heating tubes 4, positioned between and extending from the horizontally arranged tube-sheet l and. the angularly disposed tube-sheet 2.

Tube-sheets 1 and 2 are also provided with large central-openings 6 and 7, respectively,

"which openings are connected by a correspondingly large cylinder or tube 8, ,provid ing the customary large central opening usually employed in calandrias of this type.

Extending-around the outside of the calandria A is an enclosing rim or the like 9. provided with steam inlets 10, the calandria when assembled being positioned in and supported by the walls of the evaporator or vacuum pan B in the customary manner. The central tube 8 at its'lowerend is constructed with an outlet opening 11 connected to a pipe 12, furnishing the necessary means of draining the calandria of the condensate through the lower portion of the vacuum pan 'B. I

This improved arrangement allows for a gradual increase in the length of the heating tubes from the outer periphery of the Inn-J calandria toward the center thereof, resulting, as hereinbefore stated, in a better distribution of heating surface. It will be apparent that, as the heating steam travels from the inlet toward the center of the calandria, the pressure, and therefore the temperature, gradually falls. This is true in all calandrias of this type, and where the heating tubes are all of the same length agreater amount of heat will be present around the outer portion of the calandria than at the inner portion thereof, the tubes of equal length all presenting the same heating surface, and consequently the tubes nearest the steam entrance will become much hotter than those tubes fartherest removed from said steam entrance.

In applicants construction the heating steam as it enters the calandria is constantly coming in contact with tubes that aresuccessively increasing in length and in heating surface from the outer to the inner rows and, therefore, the total heat transference of each tube is substantially equal, owing to the fact that the liquor under treatment, upon passing through the longer tub-es, will be heated a correspondingly increased length of times, thus furnishing a uniform degree of heat throughout the entire calandria. At the same time the lower tube-sheet which remains at an angle to the horizontal, will still retain the advantages and excellent features common to all inclined calandrias, in that the effect of quick and efficient con- 7 densat-e drainage is obtained.

In calculating the lengths of the tubes in the several annular rows, it is necessary only to determine the lengths of the tubes in the outer and inner rows, as the lengths of the tubes in the intermediate rows will be a mere 'matter of mathematical calculation. The dimensions of the tubes in the outer row being fix-ed and the temperature of the entering steam and the temperature of vaporization of the juices in the calandria being observed, the evaporation in pounds of water per square foot of heating surface of these tubes is readily determined, which may be reduced to pounds of water per hour per degree of difference between the temperature of the: steam and the temperature of the medium being evaporated. Then de termining the differencebetween the temperature of the steam surrounding the inner tubes and that of the evaporatingmedium, it' is a mere matter of calculation or proportion to determine the relative lengths of the outer and inner tubes to effect the same rate of evaporation by all of-the tubes.

As a practical example, assume the outer tubesof a standard calandria to be 2 ft. in length, the temperature of the entering steam at 230 degrees (about 6 pounds gauge pressure) the'inedium being evaporated at 100 degrees F. (corresponding to 28 inches of vacuum in the-pan),there exists a maximum difference of temperature between the heating steam and the medium being evaporated of 230 degrees minus 100 degrees, or 130 degrees. Under these conditions, the outer tubes would evaporate a maximum of lbs. of water per square foot of heating surface per hour witha maximum difference of temperature of 130 degrees E, which is equivalent to .6 lb. of water per degree difference, per square foot of heating surface, per hour. It has been found in practice that the difference in the temperature of th steam entering the calandria and surrounding the outer tubes and that of the steam surrounding the inner tubes is frequently as much as 40 degrees in the early stages of the boiling operation and assuming this decrease in temperature of the steam as a basis of calculation; it follows that the the difference between the temperature of the steam about the inner tubes and the temperature of the medium being evaporated isaboutdegrees F., or 230 degreesi0 degrees degrees. Assuming the same rate of evaporation per degree in temperature, per square foot of heating surface, per hour as above, it would obviously require a greater heating surface in the inner tubesto effect evaporation at this rate, than the heating surface of the outer tubes, in the proportion of 90 degrees to 130 degrees, or about 1 to 1.44. It follows, therefore, that in a calandria having outer tubes 2 ft. long, the innertubes must be2 1.44- or 2.88 ft. long to produce theoretically equaland uniform evaporation by both the outer and inner tubes, the intermediate tubes taking a proportional length between these extremes. In actual practice, in a calandria of the type shown in the drawing in which the outer tubes are two ft. in length and 4 inches outside diameter, the inner tubes would be approximatelyB ft. in length and the length of the intermediate tube being graduated correspondingly.

From the foregoing description it'will be apparent that applicant has produced a calandria obviating the principal disadvantages heretofore present in calandrias of the tube-sheet type, without sacrificing the particular and important advantages of this type of calandria. Moreover, from a constructional advantage and the question of production, applicants calandria is much cheaper and far more convenientto manufacture than a calandria with bot-h of the tube-sheets placed on an angle and parallel to each other.

up VVha-t I claim is: In a vacuum pan, a calandria comprising an upper "horizontal tube sheet, a lower downwardly and inwardly inclined tube sheet,an inclo-sing rimp'rovided wit-h oppositely disposed steam inlets therein, a cenn .Lt)

tral conduit connecting the sheets, and circulation tubes extending between and through said sheets, said tubes increasing in length successively from the periphery towards the center of the calandria by an amount substantially commensurate with the decrease in the temperature of the steam supplied to the calandria through the steam inlets; whereby the heating eifects of all of said tubes Will be substantially equal.

In testimony whereof I aflix my signature.

, JOHN J AlMES ARMSTRONG. 

